For driving control of a joint of a robot apparatus, depending on mechanical accuracy relating to a backlash or the like, a problem is likely to arise that the robot apparatus does not establish a relationship between the joint angular velocity and the joint torque when the rotation direction of the joint changes from positive rotation to negative rotation or from negative rotation to positive rotation.
To solve the above problem, in a conventional robot apparatus in which driving is controlled in consideration of friction, the driving control is carried out by arbitrarily providing hysteresis called dead zone to a region of near zero velocity (Patent Document 1).
Meanwhile, for control of driving of a control target while friction is taken into consideration, since the control target is influenced by both of Coulomb friction and viscous friction, also it has been proposed to identify and compensate for both of them (Patent Document 2).
Furthermore, it has been proposed that a velocity of a moving object is classified into a region in which the velocity is influenced by Coulomb friction and a region in which the velocity is influenced by viscous friction based on the velocity of a moving object to estimate frictional force in each of the regions with use of a model formula of a discontinuous friction model (Non-Patent Document 1).